1. Field of the Invention
The present invention relates to a combined altitude and height-above-ground indicator for an aircraft.
Although not exclusively, it is more particularly suited to helicopters liable to travel at low or very low heights above the ground.
2. Description of Related Art
Present-day altimeters present altitude information which simply shows a flying level given with respect to a fixed reference updated by the pilot. Furthermore, the height of the aircraft above the ground being overflown, measured by a radio altimeter, has to be consulted from another device, which has a different layout and a different origin. The altitude information and the height-above-ground information are therefore currently shown on two physically separate indicators which have different resolutions and different references even though they deal with the same physical parameters. These two items of information need to be monitored and correlated with one another during some phases of flight, and this leads to a heavy workload for the pilot.
However, American Patent U.S. Pat. No. 3,595,077 describes a combined indicator comprising:
a first sensor and a second sensor which respectively sense altitude and height above ground; PA1 means of processing the measurements supplied by said first and second sensors; and PA1 means of displaying two types of information delivered by said processing means by superimposing said two items of information on the same scale against a pointer.